The present invention relates to a light emission or absorption device which is intended to be associated with at least one optical detection device including a linear array of reception photodiodes for contactless inspection of articles, in particular of glass articles or containers at high temperature.
The mass production of articles at high rate requires the organization of quality control procedures which are effective and do not lead to excessive costs. Thus, in particular for the manufacture of molded articles which leave the mold at high temperature, optical inspection devices are usually used.
French Patent Application 84/15,117 relates especially to a method and a device permitting such an inspection of glass articles manufactured by injection-blow molding. The inspection is carried out by illuminating the containers and detecting the light traversing the container which moves perpendicularly to the illumination device, by means of a linear measurement array equipped with a plurality of photodiodes. This document provides, by way of light source, a fluorescent tube whose longitudinal axis is parallel to that of the measurement array.
In the same manner, U.S. Pat. No. 4,476,533 teaches an inspection device using transmission of light emitted in the direction of a linaer array of photodiodes. British Patent 2,135,452 provides for the inspection of translucent containers by subjecting these to a rotation in front of a linear ray which is directed intermittently onto the container in a direction substantially parallel to its rotation axis. Mention may also be made of French Patent 2,475,424 and of European Patent 60,160 which both use optical systems, whether for the identification of containers or for the inspection of sheet glass.
In all these documents the light sources used are either not specified or are simply mentioned in outline.
However, it has been observed in practice that the structure of the illumination device used in the methods and devices for contactless inspection of articles was of considerable significance for the reliability of the inspection. This also applies in particular to the case in which the inspection is brought about by means of an optical detection device equipped with a linear array of reception photodiodes which are arranged in an alignment orthogonal to the movement of the articles to be inspected.